The oligomerization of propene, as well as the alkylation of benzene and toluene with propene, was evaluated at 160-240°C, 3.8 MPa, and aromatic to olefin ratios of 1:6 to 6:1 using solid phosphoric acid (SPA) as a catalyst. It was found that steric effects were more important than electronic effects in determining alkylation rate and selectivity. Monoalkylation was favored even at the lowest aromatic to olefin ratio, and the isomer distribution of dialkylated aromatics remained constant irrespective of the conversion or operating conditions. No transalkylation or alkylbenzene isomerization activity was observed. It was shown that olefin oligomerization and aromatic alkylation could be combined in a single SPA catalyzed reaction system to produce a synthetic jet fuel that meets Jet A-1 specifications.

Reduced (unsulfided) nickel catalysts can be used for hydroprocessing sulfur-free Fischer−Tropsch derived feed materials, but catalyst deactivation by metal leaching can be a problem in the presence of carboxylic acids. Leaching of reduced nickel catalysts by carboxylic acids takes place by the formation of nickel carboxylates. Carboxylic acid leaching of nickel can be prevented by operating above the carboxylate decomposition temperature, which was found to be in the range 280−305 °C for the C2−C5 nickel carboxylates. Unfortunately this is not industrially practical, because of the hydrogenolysis propensity of reduced nickel catalysts at these conditions. It was also found that nickel leaching did not monotonically increase with temperature, but was inhibited at >200 °C, probably due to polymerization of the nickel carboxylates.

Abstract:The separation of tantalum and niobium compounds has been of interest for many years, with few new developments. Classically separation is achieved by liquid-liquid extraction and most research focuses on optimizing this process. A separation method that bypasses the need for liquid-liquid extraction is reported here. The process uses dry fluorination to convert tantalum and niobium pentoxides into metal oxyfluorides. The thermal behaviour of these species are sufficiently different for separation to be achieved by preferential volatilisation.Experimental results indicate that at least two temperature ranges are suitable for separation, viz.one below 165 ºC, and one above 650 ºC.

Ammonium acid fluoride (NH 4 F·xHF) has been identified as an alternative fluorinating agent for zircon, and may provide a method by which a wide variety of anhydrous metal fluorides can be synthesized. Data on the kinetics of the reaction of NH 4 F·xHF with plasma-dissociated zircon, combined with the thermodynamic parameters, are essential for the development of an industrial process for the production of a precursor for the manufacture of zirconium metal, viz. anhydrous ZrF 4 . The reaction yields (NH 4 ) 3 ZrF 7(s) and (NH 4 ) 2 SiF 6(s) , the latter forming volatile products at relatively low temperatures, affording easy separation of silicon from the zirconium compound.Another useful aspect of the process is the possibility of recycling, since the ammonia and hydrogen fluoride in the waste stream can be recombined, making them available for re-use as the acid fluoride. It was found that the reaction constant k'' varies exponentially with temperature at a set value of x, but linearly with changes in x at a set temperature. The activation energy for the digestion is between 20 and 47 kJ.mol -1 for the values of x investigated.

In this paper, Phoenix dactylifera L. date palm seeds (RDS) were first characterized from a physicochemical point of view, in particular the proximate and ultimate composition, XRD, and SEM-EDX analyses. Based on findings RDS contains 77.4 % of total carbohydrates, 12.8 % of lignin, and a higher heating value (HHV) of 15.88 MJ kg À 1 . Immuno-labeling intensity (OD) of noncellulosic RDS fraction was also determined thanks to the ELISA technique after the dissolution of polysaccharides in ionic liquid showing the presence of mannans and xyloglucans and the absence of arabinans in date seeds, a significant amount of homogalacturonans were also detected. The thermal decomposition and kinetic of date palm seeds (RDS) using TGA-DTG, and DSC measurements were then investigated. The RDS samples were heated in the temperature ranges 25-600 °C at 5, 10, 15, and 20 °C/min. The decomposition of hemicelluloses, cellulose, and lignin, active pyrolysis of RDS, was held in a range of temperature 160-450 °C. The kinetic parameters such as activation energy (E a ) and pre-exponential factor (A) were determined for two degradation steps by using iso-conversional model-free methods. The E a and pre-exponential factor obtained by the Kissinger method are 212 kJ mol À 1 and 7.8 × 10 19 min À 1 for the first decomposition interval (I1) and 172 kJ mol À 1 and 5.96 × 10 13 min À 1 for the second decomposition interval I2. The same average parameters calculated by model-free methods are 126-156 kJ mol À 1 and 180-213 kJ mol À 1 and 3.36 × 10 14 and 7.07 × 10 17 min À 1 respectively for the first and second intervals of thermal decomposition. Indicating that activation energy decreases in the final stages of the process and that the energy required for hemicelluloses degradation is lower than that of cellulose. The most probable reaction functions have been determined for these two stages, by Coats-Redfern (CR) and Criado methods, leading to considerably improved calculation performance over the entire conversion range. The pyrolysis reaction models of RDS are described by reaction, second order F2 for cellulose and hemicelluloses. With the Arrhenius parameters obtained from the fitting model of CR, we attempt to reconstruct the temperature-dependent mass conversion curves and have resulted in generally acceptable results. Based on the Arrhenius parameter values, obtained by the Kissinger equation, the changes in entropy, enthalpy, Gibbs free energy, and lifetime predictions have been estimated for the thermal degradation processes of RDS.